Proteolytic activity, mycotoxins and andrastin A in Penicillium roqueforti strains isolated from Cabrales, Valdeon and Bejes-Tresviso local varieties of blue-veined cheeses
High quality local varieties of blue-veined cheese are made in the villages of the valleys of Cabrales, Valdeon and Bejes-Tresviso in North Spain. Penicillium roqueforti strains have been isolated from each of those blue cheeses and compared with the collection strain P. roqueforti CECT 2905 (ATCC 10110) and a strain 'Valdeon-industrial' used for large scale production of Valdeon cheese. Using molecular genetics techniques and 5.8S and 18S rRNAs and the D1-D2 regions of 28S rRNA all strains were identified as authentic P. roqueforti. These strains from local varieties of blue cheese could be distinguished from the Valdeon-industrial strain and the control strain CECT 2905 by the mitochondrial DNA restriction pattern. The industrial strain showed high levels of aspartylprotease AspA, whereas the culture collection strain showed barely detectable levels of this enzyme, as shown by proteolysis tests and by immunodetection with anti-AspA antibodies. The lipolytic activity was similar in the strains isolated from the three types of local blue cheeses. The strains isolated from the local varieties of the blue cheese produced moderate levels of PR toxin, whereas the Valdeon-industrial strains showed a higher content of this mycotoxin. All strains (except the control strain CECT 2905) showed similar levels of roquefortine C. The antitumoral compound andrastin A was produced by all strains at different levels. P. roqueforti CECT 2905 showed high ability to synthesize this compound. Andrastin A was present in all industrial and local varieties of blue cheese. The content of andrastin A was similar to that of other well-known blue cheeses from France and Denmark.